Why?
The Web has lots of stuff
- frontier beyond curated datasets
- stuff is wrapped in HTML
- HTML is transported over HTTP but composed for h2m consumption
- Intellectual Property rights bear serious consideration
API
Application Program Interface
- Built for machine-to-machine interactions
- Instructions for programs
Client / Server
- Make [R] interface with the web
- Same as h2m but now m2m
JSON
- Javascript Object Notation is a language-independent data format
- Currently the most common data data format for asynchronous client/server communication format
- Consists of key-value pairs
# from https://en.wikipedia.org/wiki/JSON
{
"firstName": "John",
"lastName": "Smith",
"isAlive": true,
"age": 25,
"address": {
"streetAddress": "21 2nd Street",
"city": "New York",
"state": "NY",
"postalCode": "10021-3100"
},
"phoneNumbers": [
{
"type": "home",
"number": "212 555-1234"
},
{
"type": "office",
"number": "646 555-4567"
},
{
"type": "mobile",
"number": "123 456-7890"
}
],
"children": [],
"spouse": null
}
Example
Demonstration
library(jsonlite)
# https://cran.r-project.org/web/packages/jsonlite/vignettes/json-aaquickstart.html
# for building tibbles
library(tidyverse)
Single JSON array
When the server response is a single JSON array, JSONlite makes viewing the data pretty simple.
oneJSONresult <- fromJSON("http://www.omdbapi.com/?t=rocky&y=&plot=full&r=json")
Let’s see the results in the next slide
oneJSONresult
$Title
[1] "Rocky"
$Year
[1] "1976"
$Rated
[1] "PG"
$Released
[1] "03 Dec 1976"
$Runtime
[1] "120 min"
$Genre
[1] "Drama, Sport"
$Director
[1] "John G. Avildsen"
$Writer
[1] "Sylvester Stallone"
$Actors
[1] "Sylvester Stallone, Talia Shire, Burt Young, Carl Weathers"
$Plot
[1] "Rocky Balboa is a struggling boxer trying to make the big time, working as a debt collector for a pittance. When heavyweight champion Apollo Creed visits Philadelphia, his managers want to set up an exhibition match between Creed and a struggling boxer, touting the fight as a chance for a \"nobody\" to become a \"somebody\". The match is supposed to be easily won by Creed, but someone forgot to tell Rocky, who sees this as his only shot at the big time."
$Language
[1] "English"
$Country
[1] "USA"
$Awards
[1] "Won 3 Oscars. Another 16 wins & 21 nominations."
$Poster
[1] "https://images-na.ssl-images-amazon.com/images/M/MV5BMTY5MDMzODUyOF5BMl5BanBnXkFtZTcwMTQ3NTMyNA@@._V1_SX300.jpg"
$Metascore
[1] "N/A"
$imdbRating
[1] "8.1"
$imdbVotes
[1] "387,927"
$imdbID
[1] "tt0075148"
$Type
[1] "movie"
$Response
[1] "True"
The vector object behaves as you would expect in R.
- You can list all the variable names.
names(oneJSONresult)
[1] "Title" "Year" "Rated" "Released" "Runtime" "Genre" "Director" "Writer" "Actors"
[10] "Plot" "Language" "Country" "Awards" "Poster" "Metascore" "imdbRating" "imdbVotes" "imdbID"
[19] "Type" "Response"
- List an individual element
oneJSONresult$Title
[1] "Rocky"
oneJSONresult$Awards
[1] "Won 3 Oscars. Another 16 wins & 21 nominations."
A JSON Matrix
The results of this code-snippet react differently between the console, the Notebook script (console), and the Notebook HTML output. In the Notebook script-output you can find the component name, in this case dollar-search: $Search. Or, you can use bracket notation: [[1]]. Once you identify the component name, it’s easier to identify the element names.
jsonSeriesResutlsMatrix <- fromJSON("http://www.omdbapi.com/?s=rocky&type=series&r=json&page=1")
jsonSeriesResutlsMatrix
$Search
$totalResults
[1] "20"
$Response
[1] "True"
Call the search results and coerce the JSON array into a data frame.
jsonSeriesResutlsMatrix$Search
jsonSeriesResutlsMatrix$Search$Title
[1] "Rocky and His Friends" "Dr. Jeff: Rocky Mountain Vet" "Rocky Jones, Space Ranger" "Rocky Mountain Law"
[5] "Rocky King, Detective" "Rocky Road" "Rocky Mountain Bounty Hunters" "Rocky + Drago"
[9] "Rocky Point" "Rocky Star"
Resources
- RStudio httR video
- JSONlite package
- listof images
- Movies of 1976
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QiBhcGkgDQoNCi0gaHR0cDovL3d3dy5vbWRiLm9yZy8NCiAgICAtIGxpa2UgaHR0cDovL2ltZGIuY29tLw0KLSBubyBBUEkga2V5cyByZXF1cmllZA0KLSBodHRwOi8vd3d3Lm9tZGJhcGkuY29tLw0KDQotLS0gDQoNCiMjIyBEZW1vbnN0cmF0aW9uDQoNCg0KYGBge3IgbG9hZC1saWJyYXJ5LXBhY2thZ2UsIG1lc3NhZ2U9RkFMU0UsIHdhcm5pbmc9VFJVRX0NCmxpYnJhcnkoanNvbmxpdGUpDQojIGh0dHBzOi8vY3Jhbi5yLXByb2plY3Qub3JnL3dlYi9wYWNrYWdlcy9qc29ubGl0ZS92aWduZXR0ZXMvanNvbi1hYXF1aWNrc3RhcnQuaHRtbA0KDQojIGZvciBidWlsZGluZyB0aWJibGVzDQpsaWJyYXJ5KHRpZHl2ZXJzZSkNCmBgYA0KDQoNCiMjIyBTaW5nbGUgSlNPTiBhcnJheQ0KV2hlbiB0aGUgc2VydmVyIHJlc3BvbnNlIGlzIGEgc2luZ2xlIEpTT04gYXJyYXksIEpTT05saXRlIG1ha2VzIHZpZXdpbmcgdGhlIGRhdGEgcHJldHR5IHNpbXBsZS4NCmBgYHtyIHNpbmdsZUpTT05yZXN1bHR9DQpvbmVKU09OcmVzdWx0IDwtIGZyb21KU09OKCJodHRwOi8vd3d3Lm9tZGJhcGkuY29tLz90PXJvY2t5Jnk9JnBsb3Q9ZnVsbCZyPWpzb24iKQ0KYGBgDQoNCkxldCdzIHNlZSB0aGUgcmVzdWx0cyBpbiB0aGUgbmV4dCBzbGlkZQ0KDQotLS0NCg0KYGBge3J9DQpvbmVKU09OcmVzdWx0DQpgYGANCg0KDQotLS0gDQoNCiMjIyMjIFRoZSB2ZWN0b3Igb2JqZWN0IGJlaGF2ZXMgYXMgeW91IHdvdWxkIGV4cGVjdCBpbiBSLiAgDQoNCi0gWW91IGNhbiBsaXN0IGFsbCB0aGUgdmFyaWFibGUgbmFtZXMuDQoNCmBgYHtyfQ0KbmFtZXMob25lSlNPTnJlc3VsdCkNCmBgYA0KDQotIExpc3QgYW4gaW5kaXZpZHVhbCBlbGVtZW50DQoNCg0KYGBge3J9DQpvbmVKU09OcmVzdWx0JFRpdGxlDQpgYGANCg0KYGBge3J9DQpvbmVKU09OcmVzdWx0JEF3YXJkcw0KYGBgDQoNCg0KLS0tDQoNCiMjIyBBIEpTT04gTWF0cml4DQpUaGUgKipyZXN1bHRzIG9mIHRoaXMgY29kZS1zbmlwcGV0IHJlYWN0IGRpZmZlcmVudGx5KiogYmV0d2VlbiB0aGUgKmNvbnNvbGUqLCB0aGUgKk5vdGVib29rIHNjcmlwdCogKGNvbnNvbGUpLCBhbmQgdGhlICpOb3RlYm9vayBIVE1MKiBvdXRwdXQuICBJbiB0aGUgTm90ZWJvb2sgc2NyaXB0LW91dHB1dCB5b3UgY2FuIGZpbmQgdGhlIGNvbXBvbmVudCBuYW1lLCBpbiB0aGlzIGNhc2UgZG9sbGFyLXNlYXJjaDogYCRTZWFyY2hgLiAgT3IsIHlvdSBjYW4gdXNlIGJyYWNrZXQgbm90YXRpb246IGBbWzFdXWAuICBPbmNlIHlvdSBpZGVudGlmeSB0aGUgY29tcG9uZW50IG5hbWUsIGl0J3MgZWFzaWVyIHRvIGlkZW50aWZ5IHRoZSBlbGVtZW50IG5hbWVzLg0KYGBge3J9DQpqc29uU2VyaWVzUmVzdXRsc01hdHJpeCA8LSBmcm9tSlNPTigiaHR0cDovL3d3dy5vbWRiYXBpLmNvbS8/cz1yb2NreSZ0eXBlPXNlcmllcyZyPWpzb24mcGFnZT0xIikNCmpzb25TZXJpZXNSZXN1dGxzTWF0cml4DQpgYGANCg0KLS0tICANCg0KIyMjIENhbGwgdGhlIHNlYXJjaCByZXN1bHRzIGFuZCBjb2VyY2UgdGhlIEpTT04gYXJyYXkgaW50byBhIGRhdGEgZnJhbWUuDQpgYGB7cn0NCmpzb25TZXJpZXNSZXN1dGxzTWF0cml4JFNlYXJjaA0KYGBgDQoNCi0tLSANCmBgYHtyfQ0KanNvblNlcmllc1Jlc3V0bHNNYXRyaXgkU2VhcmNoJFRpdGxlDQpgYGANCg0KDQojIyBSIFBhY2thZ2VzIC0tIFJlbGF0ZWQNCg0KKlBlb3BsZSB3aG8gdXNlIEpTT05saXRlIGFsc28gdXNlLi4uKg0KDQoqIFtodHRyXShodHRwczovL2NyYW4uci1wcm9qZWN0Lm9yZy93ZWIvcGFja2FnZXMvaHR0ci8pIC0tIGNhbGxzIEpTT05saXRlIGluIHNlcnZpY2UgdG8gbWFqb3IgZ29hbCBvZiBtYW5hZ2luZyBIVFRQIA0KKiBbcnZlc3RdKGh0dHBzOi8vYmxvZy5yc3R1ZGlvLm9yZy8yMDE0LzExLzI0L3J2ZXN0LWVhc3ktd2ViLXNjcmFwaW5nLXdpdGgtci8pIC0tICB1c2VkIGZvciBodG1sIHBhcnNpbmcNCg0KIyMgUmVzb3VyY2VzIA0KDQotIFJTdHVkaW8gaHR0UiB2aWRlbw0KLSBKU09ObGl0ZSBwYWNrYWdlDQotIGxpc3RvZiBpbWFnZXMNCi0gTW92aWVzIG9mIDE5NzYNCiAgICAtIFtPTURCIFRvcCBNb3ZpZXNdKGh0dHA6Ly93d3cub21kYi5vcmcvZW5jeWNsb3BlZGlhL3llYXIvMTk3Ni9zdGF0aXN0aWNzKQ0KICAgIC0gW0lNREIgTW9zdCBQb3B1bGFyXShodHRwOi8vd3d3LmltZGIuY29tL3llYXIvMTk3Ni8pDQoNCg==